This invention relates in general to universal joints for vehicle drive train systems. More specifically, this invention relates to an improved structure for preventing relative rotational movement between a bearing cap mounted on a cross of a universal joint and an end yoke connected thereto.
Universal joints are well known devices which provide a driving connection between two members adapted to rotate about non-aligned axes of rotation. Universal joints are widely used between rotatable drive shaft sections in vehicle drive train systems. A typical universal joint structure includes a cross having a central body portion with four cylindrical trunnions extending outwardly therefrom. The trunnions are oriented in a single plane and extend at right angles relative to one another. A hollow cylindrical bearing cap is mounted on the end of each of the trunnions. Needle bearings or similar means are provided between the outer cylindrical surfaces of the trunnions and the inner cylindrical surfaces of the bearing caps to permit relative rotational movement therebetween. The beating caps which are mounted on a first opposed pair of the trunnions can be connected to a first end yoke secured to an end of a first drive shalt section, while the bearing caps mounted on a second opposed pair of the trunnions can be connected to a second end yoke secured to an end of a second drive shaft section.
During operation, the first and second drive shaft sections, as well as the universal joint connected therebetween, rotate as a unit. If the axes of rotation of the first and second drive shaft sections are co-axially aligned, then no angular movement occurs between the either of the end yokes and the universal joint cross. Thus, the bearing caps remain stationary (i.e., do not rotate) relative to the trunnions upon which they are mounted as the entire unit rotates. However, when the axes of rotation of the first and second drive shaft sections are not coaxially aligned, a small amount of oscillating rotational movement occurs between each of the end yokes and the universal joint cross. Inasmuch as the bearings caps are connected to the end yokes, the beating caps will rotate a small amount back and forth relative to the trunnions upon which they are mounted. When this oscillating movement occurs, it is desirable that the beating caps be positively restrained from rotating relative to the end yokes, so that all relative rotational movement occurs between the bearing caps and the trunnions upon which they are mounted. Relative movement between the bearing caps and the end yokes can result in wear on the respective engaging surfaces, possibly resulting in undesirable looseness in the driving connection therebetween and premature failure of the universal joint. These problems can be especially pronounced when the drive shafts and universal joints are relatively large in size and are subjected to relatively heavy loads, such as might be encountered in heavy duty trucks.
Several structures are known in the art for preventing relative rotation between the bearing caps and the end yokes. For example, it is known to weld plates onto the end surfaces of the bearing caps and to bolt such plates to the end yokes. However, this structure, as well as other known anti-rotation structures, requires extra parts and additional labor to install. Consequently, these known structures undesirably increase the cost and complexity of the universal joint. Accordingly, it would be desirable to provide an improved anti-rotation structure for a universal joint which is simple and inexpensive to construct and assemble, and further which is particularly well suited for physically large drive shafts which are subjected to heavy loads.